Production of sound images on films or plates by means of the chromate process



Aug. 21, 1934. c. ROEHRICH 1,971,276 PRODUCTION OF SOUND IMAGES ON FILMS OR PLATES BY MEANS OF THE CHROMATE PROCESS Filed June 17, 1929 3 7/ Col/aid layer, sensirized fir/'zardemhy A fransparen/support 7 9 7 9 llllllllll IIIIIIIII II" II V "Ill, I llre blue green black /n ventor':

AZZOr/wy Patented Aug. 21, 1934 UNITED STATES PATENT OFFICE PRODIFUTION OF SOUND IMAGES ON FILMS on PLATES BY MEANS or The enac- MATE PROCESS Application June 17, 1929, Serial No. 371,733 In Germany June 20, 1928 27 Claims. (01. sis-16.2)

The present invention, broadly stated, relates to the production of sound films, and is more particularly concerned with a novel method and means for the photo-electric reproduction of sounds.

In order to facilitate a ready understanding of the invention, the state of the art, as far as it concerns this case, will be briefly stated.

The photo-electric reproduction of sounds is carried out by irradiating a photo-electric cell from a light source and interposing between the light source and the cell a moving film carrying the sound pictures. These sound pictures are carried on the film in iormof a variously shaded tape, the various shades corresponding to the various sounds. In the past films sensitized with a silver salt were used for this purpose, and therefore, the sound pictures consisted of the usual silversalt pictures. Such silver salt pictures are of a dark shade, and absorb a considerable part of the light, which has to permeate the film. Hence, strong sources of light were required for the operation of a system using such films.

Now, such silversalt pictures are granular; the shades being composed of numerous closely adjoining dark colored granula. Between the individual granula there are spaces, and when strong sources of light are used, which, as has been mentioned, are required in case of such silversalt films, the light permeates between these granula, thereby causing an unsatisfactory reproduction of the sounds.

One object of the present invention is to produce silverfree sound pictures for photo-electric reproduction, instead of silversalt sound pictures.

Another object is to use chromate sensitized films in the exposure of the sound pictures, thereby producing silverfree sound pictures from which silverfree copies may be made.

Another object of the invention is to produce a silverfree sound record from which the sounds can be photoelectrically reproduced.

Still another object of the invention consists in suitably dyeing the sound pictures thus produced, whereby modulation of the sound reproduction is effected.

A further object is to dye the silverfree sound pictures sectionally with diiferent dyes.

Still a further object of the invention is to provide a silver free sound picture film in which the sound pictures are stained in suitable colors, the sound picture film being adapted for photo-electrical sound reproduction.

It is to be understood that wherever the term color is used herein, it is intended to include black.

There are various advantages accruing from the invention, as briefly outlined above. An important advantage must be recognized in the fact that the new sound pictures are not granular. In a record copied for instance on a gelatine surface sensitized with chromate the dark parts or shades are not composed of a multitude of small individual dark spots, as is the case when the record is copied on a surface sensitized by means of silversalts. The dark parts or shades are in the form of an homogeneous dark area. For sound records this gives the decided advantage that no false light can therefore permeate through the spaces between the individual spots or granula in the shaded parts, whereby incorrectness in the reproduction of the sounds is avoided.

The invention is also concerned with a new 75 method of modulating sound reproduction. This part of the invention is based on the perception that by using stained sound pictures instead of the usual black and white sound pictures it is possible to change the character of the sound reproduction. This modulating of sound reproduction by suitably dyeing or staining of the sound pictures is possible partly on account of the fact that the sensitiveness of the photo-electric cell varies for diiferent colors; and partly on account of the fact thatthe sensitiveness of layers sensitized for photographic purposes also varies for different colors.

In a previous part of the specification it has been suggested to use for sound pictures silverrree surfaces, such as surfaces sensitized by means of bichromates, instead of silversalt sensitized surfaces. The fact that thus prepared sound pictures can be readily dyed with various colors enables modulating the sounds within a large range. This is an extremely important feature of the invention. At first glance it may appear that any picture, including silversalt pictures, may be dyed. This is true, theroretically. There are, however, very essential differences between dyeing silversalt pictures and dyeing silverfree pictures, such as chromate gelatine pictures. In the following these differences will be particularly described with regard to the two main types of colored silversalt films.

There is a well known kind of colored silversalt film in which the dye is distributed uniformly over the entire area of the film. This kind of film is frequently used for'visible picture films, showing, for instance, a moonlight scene all colored violet, or asu'nset scene all colored red. In this kind of colored films the color is superposed over the different shades of the picture and in the dark parts the effect of the blaclg shade exceeds the effect of the color applied to the film to such an extent as to render the color practically ineffective.

In case of the new sound records consisting for instance of chromate gelatine pictures, where the dye is absorbed in accordance with the different degrees of hardness of the film, the different shades of the sound record are produced by the different densities of the color only, and not by black or gray shades with a superimposed color of one and the same density all over the film.

Therefore in these colored chromate gelatine sound records and the like the color can exert its full action undisturbed by any dark background, as no such background exists even in the full-tone areas of the record.

The fact that stained silverfree sound pictures are of a greater transparency as compared with the colored silversalt sound pictures must be listed as an advantage also, because it results in saving of light intensity. It is therefore possible to employ considerably weaker sources of light for reproducing sounds from these pictures.

I may refer to still a second kind of well known stained silversalt pictures by describing a method of manufacturing these pictures. At first a usual black and white silvers'alt picture is made by one of the wellknown developing methods; the black and white copy is then bleached,

.whereby the dark shades disappear, leaving, how

ever, at the respective parts of the film opaque areas. The film is then treated with suitable chemical solutions which react with the opaque areas, whereby these areas are colored. It is apparent that in this second kind of colored silversalt pictures also, the color is superposed over an opaque layer, and this superposition of dark shade and color oftentimes results in inoperativeness of the record, as far as sound records are concerned. By all means, the action of the color is weakened by the superposed action of the opacity of the background.

My suggestion to use 'silverfree sound records such as bichromate gelatine sound records presents therefore great advantages also for the modulating of the sound reproduction by means of coloring the sound pictures. Not only because the newly suggested type of sound pictures can be more readily dyed than silversalt pictures, but also because the colored silverfree sound picture has superior qualities over colored silversalt pictures.

In other words, by using in the manufacture of photoelectrically photosensitive layers, sensitized for being hardened, where light struck (such as for instance bichromate gelatine) an improved photoelectric sound reproduction is achieved.

A detailed description will now follow of a number of preferred methods for manufacturing thenew sound records.

In describing various modifications of the invention, reference is made to the annexed drawing, of which Fig. l is a schematic view on a greatly enlarged scale of part of a film carrying a sound-record produced on a silversalt sensitized layer;

Fig. 2 is a corresponding schematic view with the sound-record produced on a layer free from reproduible Sound first film can be used for the production of silversalts and sensitized for a hardening procedure;

Figs. 3-6 illustrate schematically the different working steps for'producing a sound record in accordance with the invention, showing on an enlarged scale a longitudinal section of a piece of film;

Fig. '7 is a diagrammatic plan view showing schematically a part of a piece of film with sound pictures dyed in ditferent colors;

Fig. 8 is a cross-section of a piece of film carrying sound pictures and visible pictures.

Figs. 1 and 2 schematically show some essential differences between a sound record of the well-known type, i. e., a record produced on a 'silversalt sensitized layer (Fig. 1), and the new sound record. 1 designates a silversalt film, 2 a silverfree film. The shades constituting the sound records on film 1 have a grainy structure, as at 3, whereas the sound pictures 4 on film 2 are of homogeneous shade. The grains of the silver salt record spoil the sharp contours of the sound pictures. This is deleterious for the quality of sound reproduction, particularly for sounds of high frequencies, where the size of the grains comes into account with regard to the magnitude of a single sound-line, as schematically shown at 5. It may be mentioned that for sake of clearness the grainsare shown in Fig. 1 on a largely exaggerated scale.

A chromate gelatine film is exposed in any one of the well known ways for the manufacture of sound records, to the influence of a source of light, on which are superimposed the sound waves.

The sounds will appear on the chromate gelatine film in the form of a tape consisting of more or less hardened parts. This tape is called the sound picture. Many developing methods are known per se for pictures taken on surfaces sensitized to harden under the action of light. these known .methods are applicable for the new sound records, with the exception of those known developing methods only, which result in a relief picture. The film may then be treated for instance with suitable dyes which are absorbed by j the different parts of the tape according to the degree of hardness of the parts.

Describing these developing steps still in greater detail, the sound picture film may be first treated with cold water for about ten minutes.

Then a solution containing 3% of a Pinatype dye Type M (from J. G. Farbenindustrie A. G. Farbwerke Hochst) dissolved in water may be applied for about 2 to 6 minutes. Finally the film may be treated for about 5 to 10 minutes in a bath containing 5% of sulphate of copper, dissolved in water.

As already mentioned, all these steps are wellknown for manufacturing visible pictures. This further copies.

Fig. 3 schematically shows a film adapted to be used for manufacturing sound pictures in accordance with the invention. The film contains a transparent support coated with a colloid layer. For producing sound pictures the colloid layer is photo-sensitized with a suitable sensitizing agent, which causes hardening of those parts of the layer on which light falls during the exposure.

Fig. 4 schematically shows the film after ex posure. Reference number 7 designates the nonhardened sections of the colloid layer; 9 designates those sections, which during the exposure Most of Jib had received full light, and which are accordingly fully hardened, whereas 8 designates the partially hardened sections or areas, which during exposure had received some light, but less than sections 9.

Fig. 5 shows the film illustrated in Fig. 4 in a later state of manufacture. It is assumed for the example shown in Fig. 5 as well as in Fig. 6 (to be later described) that a developing method is used for the exposed film shown in fig. 4, which produces the darkest shade in the unhardened sections, leaving the fully hardened sections clear. Accordingly sections 7 show a dark black shade and sections 8 are gray, whereas sections 9 are left clear.

An arrangement which may be employed advantageously consists. in photographing the sounds first on a film sensitized by a silversalt instead of on a chromate gelatine film. The original use of films sensitized by a silversalt will often be necessary for technical reasons, because the silversalt film is appreciably more sensitive than the chromate gelatine film. The latter requires a longer exposure than might often be available for the original exposure.

The sound picture employed for actual reproduction of the sounds should however in any case be a silverfree picture. As already stated, it is suggested according to one part of the present invention to apply to the sound picture dyes or tints whichwill cause modulation of the sound reproduction. The reasons why modulation of sound reproduction can be achieved by means of coloring the sound pictures, will be now explained in greater detail. Various types of photoelectric cells are known in the art. Insofar as the present invention is not concerned with the manufacture of photoelectric cells, it is not deemed necessary to in detail describe the structure of such cells. It will sufiice for the understanding of the following explanations to point out that for practically all photoelectric cells the sensitiveness of the cell varies for lights of different colors. Some cells have a high sensitiveness for red and low sensitiveness for green; other types of cells have the maximum sensitiveness in the blue part of the spectrum, and for still other cells the maximum sensitiveness lies at still other regions of the spectrum. Apparently, sound records-of different colors will therefore, when reproduced by means of a photoelectric cell, cause different kinds of sound reproduction. For instance, in connection with a photoelectric cell having high sensitiveness in the green part, a red colored sound record would give a loud sound reproduction and a green colored record would give a dampenedreproduction.

Fig. 6 illustrates the film shown in Fig. 3 to be colored red. Sections 7 show a dark or full red tint, sections 8 are of light red color, whereas sections 9 are uncolored.

By variously dyeing certain sections on the film, it is possible to produce various modulations in one film.

Fig. 7 schematically shows a sound picture film in the first section of which the sound pictures are colored red, the sound pictures in the following sections being blue, green and black, respectively.

The sound modulating effect of suitably coloring the sound pictures may be explained from a .still different point of view. It is well known in the manufacture of visible photographic pictures to modulate the character of the picture by using color filters in the copying process. For instance color will produce a modulation of the contrasts.

in the final sound record. For example, the application of red colors to the sound picture from which the final record is copied, will accentuate the contrasts in that record, whereas the application of green colors will equalize the melody.

A modification with regard to a film combining visible pictures and sound pictures will now be explained. As is well known, a film for reproducing visual pictures and the accompanying sounds consists of two parallel sections, extending longitudinally over the entire length of the film. The wider section contains the visual pictures and the narrower section contains the sound tape. The present invention, as described in the foregoing paragraphs, may be applied with great advantage to such films. The negatives of the visual picture and of the sound picture are for this purpose copied on one chromate gelatine film. These two negatives may form one single film negative. The chrome gelatine copy is then preferably developed by treating each section differently. The visual picture section, may, e. g., be treated first with a brown dye. A bath containing 3% of Pinatype Brown Type M (from J. G. Farbenindustrie A. G., Farbwerke Hochst) dissolved in water may be applied for this purpose for about 2 to 6 minutes. After drying, both sections may be treated with a green dye, whereby a black color is produced on the visual picture film, while the sound film will be green. The green dye may be applied for to of a minute in form of a dye bath containing 2 of Pinatype Green Type M. Finally a bath containing 5% of sulphate of copper dissolved in water may be applied for 5 to 10 minutes. These baths are in themselves well known as mentioned previously. Many variations in tint and shade are possible by choosing suitable dyes. Attention must be taken, however, that only such tints are chosen which are absorbed by chrome gelatine in accordance with the degree of hardness of the different parts of the chromegelatine layer.

Fig.8 shows in cross-section part of a film which carries in side by side relation sound pictures and visible pictures. The sound picture shade 10 is green, whereas the shades on the vis-.

ible picture area 11 are black.

It is also possible to prepare a film in which one section is sensitized with a silversalt while the other section is sensitized with chome gelatine. In this case, the section sensitized with the silversalt is developed in accordance with the usual practice, and the chrome sensitized section is developed as explained above.

This method is of great practical importance, because it presents the possibility to modulate the visual picture independently of the sound picture. This is often necessary in view of the fact that the technical conditions for reproducing sounds and pictures are different.

What is claimed is:

1. As a new article of manufacture, a carrier for sound records for use in a photo-electric system, comprising a photographic film having a light exposed sensitized surface, the degree of exposure of which is the function of the sound production affording a photographic record roe - rich, the full length of said film consisting of a sequence of colored parts, each part differing in color from the adjacent parts, the colors serving to modulate the sound reproduction.

3. As a new article of manufacture, a carrier for sound records for use in a photo-electric system, comprising a photographic film having thereon a photographic sound record varying as the function of the sound, the full length of said film consisting of a sequence of colored parts, each part differing in color from the adjacent parts, the density of each color varying at different areas of the record in accord with the different sounds.

4. The method of producing sound records which comprises the steps of exposing a photographic film under a source of light responsive to sound waves, developing said film, exposing under said film a second transparent silver free film rendered insoluble whereaffected by light, and developing the sound record on said second film by means of suitable dyes leaving the soluble areas of said second film undissolved to form a suitably colored sound record.

5. The method of producing sound records which comprises the steps of exposing a photographic film under a source of light responsive to sound waves, developing said film, exposing under said film a second transparent film rendered insoluble where affected by light, and col oring different portions of said second film with different colors, whereby to effect different modulations of sound reproduction.

6. The method of producing a film containing visual pictures and photo-electrically reproducible silver free sound records comprising thesteps of copying the visual pictures onto one section of a film, copying the sound records onto the other section of said film, applying a suitable dye to one of said sections, and applying another dye to both said sections of said film.

7. The method of producing a film containing visual picture and photo-electrically reproducible sound record sections which comprises the steps of sensitizing one section of the film with silversalt, sensitizing the other section of said film with bichromates, both said sections lying adjacent each other on one and the same surface of said film, copying the visual pictures onto the silversalt sensitized section, copying the sound record on the bichromate'sensitized section, developing said visual pictures in the usual black and white shades, and producing colored sound records by applying suitable dyes to said secondly mentioned section.

both the sound record and the visual pictures, choosing said colors so that they will effect a black coloring of said visual pictures.

9. The art of modulating sound reproduction effected by means of a single photo-electric cell which consists in coloring the photographic silver free sound records with colors producing sound modulating portions, which records are carried by a photographic film rendered insoluble, where exposed to light.

10. The art of differentially modulating different parts of amelody reproduced from a sound record by means of a single photo-electric cell, which consists in dyeing different sections of the sound records with different dyes having different sensitizing effects on said photoelectric cell.

11. Aphoto-electrically reproducible sound record comprising a photographic film with hardened, partially hardened and unhardened areas, and having plane surfaces, said film being colored with a color of the visible spectrum, the density of color varying in correspondence with the different degrees of hardness.

12. A sound record comprising a film strip consisting of a sequence of partial film strips, each of said partial strips being of different color than its preceding and its succeeding strip and each of said strips having variously hardened areas, the degree of hardening varying as the function of the sound recorded.

13. A sound record consisting of a film strip comprising a sequence of red colored, green colored, blue colored, yellow colored, brown colored and black colored partial strips and each of said strips having variously hardened areas, the degree of hardening varying as the function of the sound recorded.

14. A cinematographic film containing on one and the same film surface visual pictures and silver free photo-electrically reproducible sound records, both said visual and said sound records being composed of suitably dyed hardened, partially hardened and unhardened areas, the visual pictures differing in color from the sound records.

15. A finished bichromate gelatine sound-picture film responsive to light and having a substantially even surface, the sound records consisting of gelatine areas of different degrees of hardness and different density of color, corresponding respectively to the different sounds.

16. As a new article of manufacture, a photoelectrically reproducible silver free sound record, comprising a photographic film having a light exposed surface, the degree of exposure of which is the function of the sound production affording a photographic record wherein said exposed portions are more or less hardened in accord with the variations of the sound, and said record having a substantially even surface dyed in selectively translucent colors in accordance with the variations of the sound.

17. As a new article of manufacture, a photoelectrically reproducible silver free sound record, comprising a photographic film having a light exposed surface, the degree of exposure of which is the function of the sound production affording a photographic record wherein said exposed portions are more or less hardened in accord with the variations of the sound, and said record having a substantially even surface variously dyed in accordance with the variations of the sound, said dye serving to produce modulation of the sound reproduction.

18. As a new article of manufacture, a carrier for sound and visual records for use in a photo- 1 electric system, comprising a photographic film carrying in side by side relation a visual record and a silver free sound record, the latter record having a dyed light exposed surface, the degree of exposure of which is the function of the sound production affording a photographic record wherein said exposed portions are more or less hardened in accord with the variations of the sound, and being substantially even.

19. The method of producing photo-electrically reproducible sound records which comprises the steps of exposing a bichromated gelatine film under a source of light responsive to sound waves, developing said film, exposing under said film a second transparent silver free film rendered insoluble where affected by light, and developing the sound pictures on said second film by means of dyes penetrating differentially into the exposed and unexposed areas of the second film.

20. 'As a new article of manufacture, a photographic film comprising on a light exposed surface a photo-electrically reproducible silver free sound record comprising a track containing translucent and less translucent portions of dyed gelatine, the translucency of said portions controlling the sound reproduction.

21. As a new article of manufacture, a photographic film comprising on a light exposed surface a photo-electrically reproducible silver free sound record comprising a track containing shaded portions, the said shaded portions consisting of dyed gelatine, the surface of the track being substantially even.

22. As a new article of manufacture, a carrier for sound records for use in a photo-electric system, comprising a photographic film having a light exposed surface, the exposure of which is the function of the sound produced affording a silver free photographic record wherein said exposed portions are more or less hardened in accord with the variations of the sound, said hardened and Patent No. 1,971, 276.

less hardened portions being distinguished from each other by variations in shading and the surface of said record being substantially even.

23.- As a new article of manufacture, a carrier for sound records for use in a photo-electric system, comprising a photographic film having a light exposed bichromated track, the exposure of which is the function of the sound produced, said track including a variation in shading corresponding with the variations in exposure, said variations in shading" controlling the sound reproduction.

24. As a new article of manufacture, a photographic filrn comprising on a light exposed surface a photoelectrically reproducible silver free sound record comprising a developed track having hardened and unhardened portions which are a function of the sound produced, the unhardened portions of the track varying in shading from the hardened portions.

25. As a new article of manufacture, a photographic film comprising on a light exposed surface a photo-electrically reproducible silver free sound record comprising a track with shaded parts varying in intensity as a function of the sound produced, the variations of the intensity controlling the sound reproduction.

26. As a new article of manufacture, a photographic film comprising on a light exposed surface a photo-electrically reproducible silver free sound record comprising a track containing shaded portions", the said shaded portions consisting of uniformly dyed gelatine, the surface of the track being substantially even.

27. As a new article of manufacture, a photographic film comprising ona light exposed surface a photo-electrically reproducible silver free sound. record comprising a track containing translucent and less translucent portions of uniformly dyed gelatine, the translucency pf said portions controlling the sound reproduction.

CARL ROEHRICH,

crnriricm: or CORRECTION.

August 21, 1934.

- CARL nonunion; I

It is hereby certified that error appears in the printed specification, of the above numbered patent requiring correction as follows: Page 3, line 133, for

"chome" read chrome; and page 4, line 76, claim 8, for "record" read second; and that the said Letterslatent should he read with these corrections therein that the same may conform to the record of the case in'the Patent Office.

Signed *and sealed this 5th day of February, A. D. 1935.

(Seal) time rum- "Act-momentum a ew. 

